1. Field of the Invention
This invention relates generally to a medical imaging phantom, and, more particularly, to a training system comprising a phantom heart, wherein, in an exemplary embodiment, the system is used for training related to cardiac computed tomography angiography.
2. Background of the Invention
The following information is provided to assist the reader in understanding the invention disclosed below and the environment in which it will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless clearly stated otherwise in this document. References set forth herein may facilitate understanding of the present invention or the background of the present invention. The disclosure of all references cited herein is incorporated by reference.
Computed tomography (CT) is a medical imaging technique in which digital geometry processing is used to generate a three-dimensional imaging of a region of interest within a body from a series of two-dimensional X-ray images taken around a single axis of rotation. A contrast medium injected into a patient's venous system is typically used to enhance the contrast of various structures and/or fluids within the region of interest. The development of multi-slice CT (“MSCT”) (for example, up to 64-slice) has provided both high resolution and high speed. Moreover, images with even higher temporal resolution can be generated using electrocardiogram (“EKG”) gating to correlate CT data with corresponding phases of cardiac contraction.
As MSCT enables the acquisition of sub-millimeter slices and near isotropic voxels, anatomical territories previously unacquirable are now almost routinely imaged. In particular, dynamic structures such as the coronary vasculature, are able to be imaged as a result of the MSCT scanner's ability to acquire a volumetric data set in 5-20 seconds, well within the breath-hold interval of most patients. Furthermore, the latest generation of MSCT also enables cardiac CT even in the presence of high heart-rates and arrhythmia. Cardiac CT angiography is therefore a demanding imaging regime in which the clinician must perfect his technique to maximize image quality.
Intrinsic to the quality of a cardiac CT angiography exam is the proper dosing, delivery, and timing of the iodinated contrast bolus required for image contrast enhancement. Because cardiac CT angiography is only concerned with arterial imagery during the first-pass of the contrast bolus, the timing of the scanner acquisition relative to the peak contrast enhancement in the cardiac anatomy is important. In the case of cardiac. CT angiography with MSCT scanners, the optimization and timing of the contrast bolus is crucial.
The widespread clinical adoption of multi-slice CT has lead to challenges in adapting imaging and contrast delivery techniques which were developed in connection with single-slice, helical CT scanners. Development of optimal contrast injection techniques to generate ideal contrast enhancement has been the subject of numerous CT studies. The outcomes of such studies, however, are often not comparable and interpretation controversy arises because of variations in injection technique, parameters, and contrast medium properties. A consensus for optimal injection parameters and choice of contrast media for intravenous contrast enhancement in CT-scanning has yet to be reached and further investigation is ongoing and mandatory as scanning technology advances. To best compare different injection protocols, hemodynamic values like blood pressure, blood volume and cardiac output should ideally be held constant, as these factors significantly influence contrast enhancement. With non-uniform distribution of these factors, comparison of the contrast application is difficult to assess. Furthermore, measurements of time-enhancement curves at defined anatomic sites are required to ensure an exact analysis of contrast enhancement. To obtain a time-enhancement curve, serial CT scans at one anatomic level are necessary. However, such serial scans are not feasible in a patient study as a result of the increased radiation burden of the long acquisition time.
In an attempt to avoid the increased radiation burden and expense associated with CT patient studies, use of a flow phantom to simulate or emulate convective transport properties of the cardiovascular system has been studied. Repeated injections of a contrast agent demonstrated some utility of the model in replicating the contrast enhancement pattern of the abdominal aorta in MSCT. Although utility was demonstrated for such a flow phantom, a number of significant limitations hinder the use of the flow phantom in developing improved CT injection protocols for contrast media.
It is, therefore, desirable to develop improved cardiovascular flow phantoms, models or systems for use in studies of the propagation of injectable fluids, including, for example, contrast media and/or other drugs.